RelayLLM: Efficient Reasoning via Collaborative Decoding

Chengsong Huang, Tong Zheng, Langlin Huang, Jinyuan Li, Haolin Liu, Jiaxin Huang


Abstract
Large Language Models (LLMs) for complex reasoning is often hindered by high computational costs and latency, while resource-efficient Small Language Models (SLMs) typically lack the necessary reasoning capacity. Existing collaborative approaches, such as cascading or routing, operate at a coarse granularity by offloading entire queries to LLMs, resulting in significant computational waste when the SLM is capable of handling the majority of reasoning steps. To address this, we propose RelayLLM, a novel framework for efficient reasoning via token-level collaborative decoding. Unlike routers, RelayLLM empowers the SLM to act as an active controller that dynamically invokes the LLM only for critical tokens via a special command, effectively "relaying" the generation process. We introduce a two-stage training framework, including warm-up and Group Relative Policy Optimization (GRPO) to teach the model to balance independence with strategic help-seeking. Empirical results across six benchmarks demonstrate that RelayLLM achieves an average accuracy of 49.52%, effectively bridging the performance gap between the two models. Notably, this is achieved by invoking the LLM for only 1.07% of the total generated tokens, offering a 98.2% cost reduction compared to performance-matched random routers.
Anthology ID:
2026.findings-emnlp.524
Volume:
Findings of the Association for Computational Linguistics: EMNLP 2026
Month:
October
Year:
2026
Address:
Budapest, Hungary
Editors:
Hung-Yi Lee, Sunipa Dev, Jessy Li, Desmond Elliott
Venue:
Findings
SIG:
SIGDAT
Publisher:
Association for Computational Linguistics
Note:
Pages:
10993–11012
Language:
URL:
https://aclanthology.org/2026.findings-emnlp.524/
DOI:
Bibkey:
Cite (ACL):
Chengsong Huang, Tong Zheng, Langlin Huang, Jinyuan Li, Haolin Liu, and Jiaxin Huang. 2026. RelayLLM: Efficient Reasoning via Collaborative Decoding. In Findings of the Association for Computational Linguistics: EMNLP 2026, pages 10993–11012, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
RelayLLM: Efficient Reasoning via Collaborative Decoding (Huang et al., Findings 2026)
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PDF:
https://aclanthology.org/2026.findings-emnlp.524.pdf